Question: If $a + b + c = -4$ and $x + y = -9$, what is $-b + 2x + 2y - a - c$ ?
$= -a - b - c + 2x + 2y$ $= (-1) \cdot (a + b + c) + (2) \cdot (x + y)$ $= (-1) \cdot (-4) + (2) \cdot (-9)$ $= 4 - 18$ $= -14$